Decontamination of fluids or objects contaminated with chemical or biological agents using a distributed plasma reactor

ABSTRACT

Apparatus and method for using a non-thermal plasma or corona discharge generated at multiple points and distributed to decontaminate surfaces and objects contaminated with chemical or biological agents. The corona discharge can be generated using very short high voltage pulses. The pulsed corona discharge can be directed at a contaminated surface through the unbraided strands at an end of a dielectric covered conductor. Another pulsed discharge embodiment incorporates a primary coil surrounding a chamber having a void filled with a plurality of secondary coils. A silent corona discharge can be generated using a variety of different configurations of a dielectric coated electrode and a bare electrode. The silent discharge is produced at all intersections between the dielectric covered electrode and the bare electrode. In one embodiment the apparatus comprises a blanket-like structure that is useful for decontaminating surfaces or decontaminating a fluid passing between spaced-apart bare electrodes.

This application is a divisional application, based on prior applicationSer. No. 09/311,944, now U.S. Pat. No. 6,455,014 filed on May 14, 1999,the benefit of the filing date of which is hereby claimed under 35U.S.C. § 120.

GOVERNMENT RIGHTS

This invention was made under contract with the United States Departmentof Defense, under Contract Numbers N68335-98-C-0211 and F49620-98-0079,and the United States government may have certain rights in theinvention.

FIELD OF THE INVENTION

This invention relates to the decontamination of fluids, surfaces andobjects, and more specifically to the use of an energy source for thedecontamination of fluids, surfaces and objects contaminated withchemical or biological agents.

BACKGROUND OF THE INVENTION

The use of a non-thermal plasma to destroy pollutants is known. Anon-thermal plasma is a plasma in which electrons, rather than a gas,are excited. Ozone generators commonly use a non-thermal plasma toproduce ozone. Devices that produce non-thermal plasmas are oftenreferred to as corona discharge generators. These devices generallyoperate by using very short duration, high voltage pulses (pulsed coronadischarge) applied to an electrode. A corona discharge generator thatemploys a dielectric coating on the electrode is sometimes referred toas a barrier or silent corona discharge device. Tesla coils are oftenused as the high voltage source for a pulsed corona discharge; however,the pulsed corona discharge produced by a Tesla coil is often quiteloud.

Recently, non-thermal plasmas have been used to remove pollutants fromgas streams. U.S. Pat. No. 4,954,320, “Reactive Bed Plasma AirPurification,” describes one such use of a non-thermal or coronadischarge device used to detoxify a gas stream by passing the gas streamthrough a non-thermal plasma. The reactive bed plasma device describedtherein produces an active plasma, which yields energetic free electronsand highly reactive chemical species, especially oxygen atoms, topromote rapid oxidative decomposition of the contaminants in the airstream. This oxidation is similar to the process of incineration withthe most notable difference being the dramatically reduced operatingtemperatures of the reactive bed plasma device. Electron impact is thedriving force of plasma-induced decomposition, because it creates morefree electrons, ions, reactive neutrals, and radicals. Another result ofdirect energy input at the quantum level is the emission of ultravioletlight from nitrogen molecules in the surrounding air. This ultravioletradiation is capable of breaking some chemical bonds, ionizing manycompounds, and disinfecting selected biological contaminants uponprolonged exposure.

While the prior art seems to suggest that a non-thermal plasma may beuseful for treating a stream of gas, there is much less teaching of howto apply a non-thermal plasma to the decontamination of a surface or anobject. Experimental chambers have been constructed to batch treat smallobjects with a non-thermal plasma. While such chambers can be useful intreating small, easily handled objects, it would be desirable to developa system that enables a non-thermal plasma to destroy contaminants onthe surfaces of large objects. It would further be desirable to developa decontamination system that can distribute a non-thermal plasma to awide variety of contaminated materials, including surfaces, objects, andfluids. The prior art does not teach or suggest how such a distributednon-thermal plasma generator can be achieved to provide for theindependent or simultaneous decontamination of surfaces, object, orfluids.

While generally planar surfaces can be decontaminated using anon-thermal plasma generator that does not exhibit much dimensionalflexibility, the decontamination of an irregularly-shaped object havingnon-planar surfaces would require a non-thermal plasma generatorsufficiently large and flexible enough to drape over the object, so thatthe non-thermal plasma can “blanket” the object to be treated. The priorart does not teach or suggest how such a dimensionally flexiblenon-thermal plasma generator can be achieved.

An additional drawback of prior art non-thermal plasma generators istheir relatively high power requirements. While such power levels asrequired for prior art devices may be readily supplied for compactnon-thermal plasma generators, substantially larger non-thermal plasmagenerators will require correspondingly greater levels of power. Thus, arelatively large non-thermal plasma generator could not be easilypowered by a portable power source, such as a battery. It is desirablethat a non-thermal plasma generator based decontamination system scaledup to a relatively large size (able to decontaminate an object the sizeof a vehicle, for example) should still require power levels providableby portable power supplies. It would be further desirable that smallernon-thermal plasma generator based decontamination systems be powered bysmall batteries, such that non-thermal plasma generator baseddecontamination systems can be incorporated into small products such aspersonal air purifying respirators (APRs). The prior art also does notteach or suggest such systems.

While the prior art teaches using a non-thermal plasma to destroy thepollutants in a gas stream, there exists a wide range of chemical andbiological agents that can contaminate surfaces, objects, or fluids, thedestruction of which is not discussed in the prior art. Releases ofchemicals from farms, factories and homes can contaminate soils. Fungiand spores can contaminate seeds and foodstuffs, and even the soil usedto grow crops. Disease causing microorganisms are frequently present onsurfaces, objects, and within the air. Allergens and toxins arefrequently present in the outside ambient air, as well as the air withinbuildings (i.e., the “sick building syndrome”).

Additionally, potential terrorist use of chemical and biological agentsrepresents an ever-growing threat to populations and property. Therelease of the chemical warfare agent Sarin in the Tokyo subway systemby the Aum Shinrikyo cult has drawn widespread attention to thepotential use of chemical and biological agents in attacks by terroristor dissident groups. Also of concern is the fact that use of chemicaland biological warfare agents by foreign powers during military actionsseems much more likely in view of events in the Middle East during thelast decade. Military vehicles and other objects exposed to chemical andbiological contamination represent a hazard if their surfaces arecontacted by unprotected personnel. Decontamination of an area or objectafter the actual or suspected release of such agents thus posessignificant challenges and risks.

It therefore would be desirable to develop a decontamination system thatis effective against a wide range of biological and chemical agents,while minimizing incidental damage to the surface or object beingdecontaminated. It would further be desirable for such a decontaminationsystem to have a low power requirement so that batteries or otherreadily portable power sources could be employed to energize the system.A desirable system of this type should operate at ambient pressure andtemperature and should not consume large quantities of reagents norproduce large quantities of waste byproducts. A desirabledecontamination system should be able to readily destroy contaminantsdisposed within cracks or crevices of a surface or object. Finally, sucha system should be well adapted to decontaminating almost any fluidstream, such as breathing or medical air; as well as almost any surface,such as floors, desks, or walls, and more complex objects, such asirregularly-shaped tools, vehicles, and other equipment.

SUMMARY OF THE INVENTION

In accord with the present invention, apparatus are defined fordetoxifying chemical or biological agents. These agents may be on asurface or entrained in a fluid. The distributed plasma reactorapparatus includes a non-thermal plasma generator, which when activatedby a sufficiently high voltage, produces a plasma discharge. The plasmadischarge is adapted to be positioned in proximity to the chemical orbiological agents so that reactants produced by the plasma dischargedetoxify the chemical or biological agents. A power source capable ofenergizing the non-thermal plasma generator at a high voltage iselectrically coupled to the non-thermal plasma generator to activate it.

In one preferred embodiment, the distributed plasma reactor comprises alarge surface of distributed electrodes, or “plasma blanket,” which isadapted to be disposed adjacent to a surface to be decontaminated, suchthat the plasma discharge is produced near the surface. Preferably, theplasma blanket is sufficiently flexible to drape over anirregularly-shaped object having non-planar surfaces that are to bedecontaminated.

For portable applications, the power source comprises a battery and ahigh voltage inverter that converts a direct current produced by thebattery to the high voltage used to activate the plasma generator.

In several embodiments, the distributed plasma reactor comprises asilent discharge type non-thermal plasma generator, while in otherembodiments, the distributed plasma reactor comprises a pulse dischargetype non-thermal plasma generator.

In the silent discharge type, the non-thermal plasma generator includesone or more dielectric covered electrodes and one or more bare electrodethat are connected to the power source so that the high voltage isapplied between the dielectric covered electrodes and the bareelectrodes. In one embodiment, the bare electrode is formed in anaccordion-folded pleated configuration and the dielectric coveredelectrodes pass through adjacent pleats of the bare electrode.

To decontaminate a larger area, the distributed plasma reactor includesa plurality of dielectric covered electrodes and may include a pluralityof bare electrodes. In one preferred form, the bare electrode comprisesa conductive mesh that is relatively flexible.

One embodiment of a plasma blanket includes a sheet of non-conductivematerial that is substantially parallel to the plurality of dielectriccovered electrodes. This sheet serves to direct the plasma dischargeonto the surface to be decontaminated.

In one preferred embodiment, the bare electrode is helically wrappedaround the dielectric covered electrode. A plurality of bare anddielectric covered electrodes of this type can be attached to andsupported by a flexible substrate.

The bare electrode can be formed as a sheet, which may comprise a metalfoil, or a conductive mesh. The dielectric covered electrode preferablyextends through the bare electrode. Two or more bare electrodesconfigured as sheets can be spaced apart from each other in parallel, todefine a treatment volume through which a contaminated fluid isconveyed.

A plasma discharge is produced at each intersection where a bareelectrode and a dielectric covered electrode overlap, intersect, orwhere the bare electrode is helically coiled about the dielectriccovered electrode.

In another embodiment of the distributed plasma reactor, a dielectriccovered electrode has a first end electrically coupled to the powersource, and a non-thermal corona discharge is generated at a secondopposite end of the dielectric covered electrode. Preferably, thedielectric covered electrode further comprises a multi-strandedconductor, and at the second end of the dielectric covered electrode,the conductor is separated into individual strands, such that anon-thermal corona discharge is generated by each individual strand.This embodiment is excited by a high frequency pulsed source.

In still another embodiment, the distributed plasma reactor comprises anon-conductive substrate supporting a plurality of spaced-apart pointelectrodes and a plurality of spaced-apart dielectric spacers. Theplurality of electrodes and the plurality of dielectric spacers areconnected to a surface of the non-conductive substrate and extend awayfrom the surface. The dielectric spacers extend substantially fartherfrom the surface than the point electrodes to maintain a space betweenthe point electrodes and the surface to be decontaminated, preventingthe point electrodes from shorting to ground on that surface.

Another aspect of the present invention is directed to a method fordecontaminating a substance by destroying a toxic material that hascontaminated the substance. The method includes the step providing apower source that produces a voltage sufficiently great to generate aplasma discharge. A distributed plasma reactor is positioned proximateto the substance that is to be decontaminated. The distributed plasmareactor is then activated with the power source, producing a non-thermalplasma discharge that destroys the toxic material, therebydecontaminating the substance. Other functional steps of the method aregenerally consistent with the description of the apparatus set forthabove.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 schematically illustrates a portion of a barrier or silent coronadischarge generator;

FIG. 2 is an isometric schematic view of an “inline” distributed plasmareactor of the silent discharge type having a bare electrode in ahelical configuration, wrapping around a dielectric covered electrode;

FIG. 3 is an isometric schematic view of a portion of a plasma blanketcomprising a plurality of distributed plasma reactors of the silentdischarge type in a woven configuration;

FIG. 4 is an isometric view of a portion of another embodiment of aplasma blanket comprising a distributed plasma reactor of the silentdischarge type having a bare electrode in an accordion foldconfiguration, with a dielectric covered electrode passing through eachpleat of the bare electrode;

FIG. 5 is a schematic plan view of another embodiment of a plasmablanket that incorporates a plurality of flexible inline distributedplasma reactors of the silent discharge type, such as shown in FIG. 2,mounted on a flexible substrate;

FIGS. 6A and 6B schematically illustrate a pulsed corona dischargegenerator having a dielectric covered braided electrode terminating in aplurality of individual strands, energized by a Tesla coil;

FIG. 7 is a schematic view of a plasma blanket comprising distributedplasma reactors of the pulsed discharge type that includes a pluralityof bare pin electrodes on a supporting substrate, and dielectric spacersto maintain the bare electrodes spaced apart from a grounded surface;

FIGS. 8A and 8B are isometric views illustrating a silent coronadischarge generator, showing a single dielectric covered electrodepassing vertically and at an acute angle through a bare electrode sheet,respectively;

FIG. 9 is an isometric view schematically illustrating a portion of adistributed plasma reactor comprising a plurality of silent coronadischarge generators like those shown in FIGS. 8A and 8B;

FIG. 10 is an isometric view schematically illustrating a portion of adistributed plasma reactor in which a plurality of dielectric coveredelectrodes like those shown in FIGS. 8A and 8B pass through a pluralityof spaced-apart bare electrode sheets;

FIG. 11 is a cross-sectional isometric view of an embodiment of adistributed plasma reactor in which the bare electrodes define a volumethrough which a contaminated fluid flows;

FIG. 12 is an elevational view of the embodiment of FIG. 11;

FIG. 13 is a schematic view of a distributed plasma reactor of thepulsed discharge type that includes a primary coil surrounding aninternal treatment volume that is completely packed with a plurality ofsmall secondary coils;

FIG. 14 is an isometric schematic view of one of the secondary coilsused to fill the void spaces of the treatment volume in the distributedplasma reactor of FIG. 13;

FIG. 15 is an isometric schematic view of a primary coil that includes aplurality of spark gaps for use with the distributed plasma reactor ofFIG. 13; and

FIG. 16 is a block diagram identifying the functional component of aportable distributed plasma reactor decontamination system in accordwith the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accord with the present invention, a non-thermal plasma or coronadischarge is employed to decontaminate fluid streams, objects andsurfaces that have been contaminated with chemical or biological agents.Such contaminants are expected to include, but are not limited to,chemical agents, biological agents, chemical and biological warfareagents, disease causing microorganisms, allergens, molds and fungi.Preferably such a discharge is generated at multiple locationsthroughout a given treatment volume to ensure the plasma is thoroughlydistributed throughout the treatment volume, such that overlapping zonesof a non-thermal plasma produced thereby can be used to decontaminate aselected surface, object, or volume. An important feature of the presentinvention is that non-thermal plasma based decontamination systems canbe fabricated that have very low power requirements, and which requirelow excitation voltages. A further novel feature of the presentinvention is that desired decontamination systems can be fabricatedwhich exhibit a high degree of dimensional flexibility. The term“distributed plasma reactor” as used as used herein and in the claimsthat follow means an apparatus capable of generating a non-thermalplasma that can be distributed as multiple overlapping zones over adesired treatment area. Such a distributed plasma reactor can beconfigured such that the apparatus requires minimal power to provide thedecontamination effect even for a relatively large treatment area. Thenon-thermal plasma is produced by either a silent/barrier dischargegenerator or a pulsed discharge generator. A novel feature of theinvention is that the bare electrode in the silent/barrier dischargegenerators can be in point contact with the dielectric coveredelectrode.

One purpose of the present invention is to provide apparatus that cangenerate a relatively large volume of plasma for use in decontaminatinga correspondingly large volume, while minimizing the power and voltagerequirements. Large volume plasma chambers have been built, but theseprior art chambers typically require large excitation voltages becauseof the need to fill the large chamber with plasma. In contrast, thepresent invention reduces the voltage required by minimizing thedistances between the electrodes, and by employing multiple electrodesto distribute the plasma throughout the volume. The multiple electrodespenetrate the treatment volume, so that multiple small volumes of plasmaare generated using a much lower applied voltage than required in theprior art chambers. Sufficient electrodes penetrate the treatment volumesuch that the small plasma volumes generated completely fill thechamber. In embodiments utilizing a dielectric covered electrode andbare electrode, the bare electrode can be in point contact with thedielectric. This point contact reduces the voltage required to bridgethe gap between the pair of electrodes.

In another embodiment, power consumption is reduced by minimizing thetreatment volume required to treat a fixed contaminated volume. In thisembodiment, instead of providing a large chamber that defines theextents of a fixed contaminated volume, a flexible apparatus is providedto “blanket” or envelop the contaminated volume. In this manner, thevolume in which the plasma is generated and maintained is reduced to bejust slightly larger than the contaminated volume. In a plasma chamberof a fixed size, unless the contaminated volume is essentially the samesize as the plasma chamber, power is unnecessarily expended to createand fill the large chamber with a greater volume of plasma than isactually required to treat the contaminated object (or volume). Byproviding an apparatus that conforms to the volume of the thing that isto be treated, power consumption is substantially reduced.

Many surfaces that may become contaminated with chemical or biologicagents are likely to be generally planar. In a first preferredembodiment of the invention, a distributed plasma reactor comprises ablanket-like structure that can be placed over a surface to bedecontaminated; the blanket-like structure produces a non-thermal plasmaor corona discharge. As described above, such an embodiment wouldeffectively minimize the treatment volume, and thus the power requiredto maintain a plasma. Since there is a need to decontaminate objectssuch as vehicles and weapons that have non-planar surfaces and irregularshapes, it will be apparent that the decontamination apparatus ispreferably capable of accommodating non-planar surfaces. Accordingly, bymaking the blanket-like structure sufficiently flexible, the distributedplasma reactor can be draped over an object to be decontaminated, or theobject may be wrapped in the distributed plasma generator. FIGS. 3–5 and7 are directed to embodiments that use distributed plasma reactorscomprising a blanket-like structure for decontaminating surfaces. Foreach of these embodiments, the non-thermal plasma is preferablygenerated by a multiplicity of distributed electrodes of the type shownin FIGS. 2, 8A, or 8B. The use of a plurality of such electrodes allowslower excitation voltages to be used, thus providing apparatus thatincorporate the features of low excitation voltages and relatively lowpower consumption. These embodiments are collectively referred to as“plasma blankets.”

The term “plasma blanket” as used herein means a distributed plasmareactor that is particularly well suited for use in decontaminating asurface or object. Preferably, unless an object is limited to a planarsurface, a plasma blanket used for decontaminating the object shouldexhibit a high degree of dimensional flexibility so that the plasmablanket may drape over or be wrapped around the object. While plasmablankets are particularly well suited to decontaminate surfaces orobjects, it should be noted that any fluid that is passed through orotherwise exposed to the non-thermal plasma generated by a plasmablanket will be similarly decontaminated. Thus, it should be understoodthat any embodiment of a plasma blanket described herein could also beused to decontaminate a fluid. It is envisioned that appropriatelyconfigured distributed plasma discharge reactors can be used forindependently or simultaneously decontaminating surfaces, objects, andfluids.

Another preferred embodiment of the present invention uses distributedplasma reactors specifically for the treatment of fluids. As describedabove, in the embodiment of the present invention in which a pluralityof electrodes penetrate the treatment volume, a relatively lowexcitation voltage can be used. FIGS. 9–12 are directed to embodimentsthat use distributed plasma reactors for treating fluids such as air.Such embodiments are particularly applicable for use in decontaminatingair flowing through heating, ventilation, and air conditioning (HVAC)systems for building or vehicles. Smaller devices can be easily adaptedfor personal use, such as in air purifying respirators (APRs), becauseof the particularly modest power requirements of the distributed plasmagenerator. For these embodiments, the non-thermal plasma is preferablygenerated by a silent discharge generator.

An additional preferred embodiment of the present invention similarlydistributes plasma throughout a treatment volume by generating theplasma at a plurality of locations. This embodiment comprises atreatment chamber encircled by a primary coil. The internal volume ofthe treatment chamber is filled with a plurality of small secondarycoils. A sufficient quantity of the secondary coils can be supplied tofill any volume of the treatment chamber that is not occupied by thevolume of the object to be treated. If the contaminated volume comprisesa fluid rather than an object, the entire treatment volume can be filledwith the secondary coils, and the fluid to be decontaminated may then bepassed though the treatment volume. FIGS. 13–15 are directed to thisembodiment.

FIG. 1 shows the elements required at a minimum for constructing asilent or barrier corona discharge generator 16. Such a silent coronadischarge generator can be beneficially incorporated into a distributedplasma reactor used for decontaminating fluids, surfaces, or objects.The generator includes a dielectric material 14, which shields anelectrode 12. A gap 15 separates dielectric material 14 from a bareelectrode 18. It is within gap 15 that the corona discharge occurs whena high voltage pulse produced by an appropriate source (not shown) isapplied between electrode 12 and bare electrode 18. Any contaminatedsurface on which biological or chemical agents are disposed in proximityto the corona discharge is decontaminated by it, as described above inthe Background of the Invention. While not shown, it should be notedthat a silent or barrier corona discharge generator may be constructedusing a dielectric covered electrode in place of bare electrode 18.

Empirical testing has determined that sustainable levels of non-thermalplasma can be generated by a distributed plasma reactor having an areaof only a few square centimeters comprising an electrode fabricated ofcommon 1/32 inch diameter electrical wire, when energized by a batterypower source (at about 1 watt/cm²). A high efficiency inverter andtransformer were used to provide a voltage of about 4,000 voltspeak-to-peak to energize the distributed plasma reactor in this test.The combination of an electrode having a small radius of curvature withthe compact and efficient inverter and transformer power sourcescurrently available enable a wide range of distributed plasma reactorsto be fabricated that can be energized with portable power supplies, sothat small distributed plasma reactors, suitable for use a personal APRmay be powered by very compact batteries. Larger distributed plasmareactors, such as one comprising a blanket-like structure that can bedraped over a military vehicle like a tank, may be energized withlarger, yet still portable power supplies.

It is important to note that a distributed plasma reactor comprisingelectrodes that have a very small radius of curvature tend to beinherently flexible, due to the small diameter of the electrodes. Thus,distributed plasma reactors that exhibit a large degree of dimensionalflexibility can readily be fabricated in accord with the presentinvention. Such flexibility is quite useful when the surface or objectto decontaminated is non-planar. It should also be noted that thematerial from which dielectric 14 shielded electrode 12 or bareelectrode 18 are fabricated of is not critical, as long as it is areasonable good electrical conductor. Electrodes can be wires, metalsheets, metal foils, or metal traces deposited on a substrate. Ofcourse, if it is desirable that a distributed plasma reactor exhibitsignificant dimensional flexibility, then both of the electrodes, aswell as dielectric 14, and any additional elements comprising thedistributed plasma reactor must be dimensionally flexible. While notshown, it is important to note that bare electrode 18 can touchdielectric 14 without in anyway impairing the production of anon-thermal plasma. A non-thermal plasma will be generated at any pointof contact between bare electrode 18 and dielectric 14.

FIG. 2 illustrates a first preferred embodiment of a distributed plasmareactor 16 a, in which the plasma is distributed along a helical contactin accord with the present invention. Generator 16 a includes anelectrode 12 a, which is surrounded by a dielectric material 14 a. In asimple form of this embodiment, electrode 12 a and dielectric material14 a can comprise a simple insulated wire of small diameter, such as thewire commonly used for electrical interconnections in electronic circuitassemblies. Preferably, however, electrode 12 a is a bare wireelectrode, and dielectric material 14 a is a glass or quartz tube, butother dielectric materials can be used, including plastics and othermaterials that are relatively flexible and elastomeric, and thedielectric material can be in the form of fibers, beads, foam, or almostany other configuration that provides a dielectric barrier aroundelectrode 12 a.

In distributed plasma reactor 16 a, a bare electrode 18 a is helicallycoiled or plated around dielectric material 14 a and may comprise a finefilament wire, a metallic tape, a metallic foil, or a metallic tracedeposited directly onto dielectric 14 a by lithography or vapordeposition methods. The corona discharge phenomenon generally occurs ina vicinity 15 a where bare electrode 18 a touches or crosses adjacent todielectric material 14 a, when a high voltage (e.g., 4,000 voltspeak-to-peak) is applied between electrode 12 a and bare electrode 18 a.It is important to understand that a corona discharge will occur aroundbare electrode 18 a anywhere it contacts or is adjacent to dielectricmaterial 14 a. Thus, the helical coil defined by bare electrode 18 aaround dielectric material 14 a will generate a corona discharge whenelectrode 12 a and bare electrode 18 a are energized at differentvoltage potentials, and the effect of the corona discharge will extendradially beyond the limits of the bare electrode, so that anycontaminated fluid or surface (not shown) in the vicinity of both thebare electrode and dielectric material 14 a will be decontaminated bythe resulting corona discharge and the ionized gas environment that itproduces. While the area that can be decontaminated by a singledistributed plasma reactor 16 a is finite, multiple distributed plasmareactors 16 a mounted on a flexible substrate to form a flexible plasmablanket, as is shown in FIG. 5, enable the decontamination ofsubstantially larger areas or volumes. Details of FIG. 5 are discussedbelow.

FIG. 3 illustrates a plasma blanket 17 having a woven configuration inwhich a plurality of electrodes 12 a covered with dielectric material 14a, and a plurality of bare electrodes 18 b, are woven substantiallyperpendicular to each other, producing a flexible plasma blanket of anydesired dimensions. Again, the corona discharge phenomenon will occur ateach intersection 15 b of the dielectric material 14 a coveredelectrodes 12 a and bare electrodes 18 b.

In a preferred embodiment, dielectric material 14 a covered electrodes12 a and bare electrodes 18 b are woven into a sheet or blanketsufficiently large in area to cover a surface or an object that is to bedecontaminated. Such a blanket can then be placed onto a surface that iscontaminated with any one or more of a chemical agent, a biologicalagent, a disease causing microorganism, an allergen, a spore, and/or afungi. When the blanket is energized, the corona discharge willeffectively destroy the contaminant. Preferably, dielectric material 14a covered electrodes 12 a and bare electrodes 18 a are flexible, so thatthe resulting plasma blanket will be sufficiently flexible to drape overan object, or to be wrapped around an object. Such a flexible blanketcan then be used to decontaminate irregularly-shaped objects as well asflat surfaces.

Plasma blanket 17 can be woven only of bare electrodes 18 b anddielectric material 14 a covered electrodes 12 a as shown, or theblanket can also include an additional non-conducting flexible material,such as fiberglass, natural or synthetic cloth threads, and otherfibrous material. This flexible material (not shown) can be woven into ablanket, or used as a flexible substrate upon which dielectric material14 a covered electrodes 12 a and bare electrodes 18 b are mounted (forexample, by stitching the dielectric material covered electrodes andbare electrodes onto the surface of the underlying substrate). Such aconfiguration should provide protection to the electrodes when theblanket is in use or storage. Furthermore, if the electrodes are mountedon a flexible substrate, the substrate will act to direct and containthe reactive species generated by the non-thermal plasma onto thecontaminated surface. If the plasma blanket solely comprises the wovenelectrodes as shown in FIG. 3, the corona discharge plasma will begenerated both above and below the plasma blanket, and the plasmaproduced on the side of the plasma blanket opposite that adjacent to thecontaminated surface will have less effect in decontaminating thesurface. In contrast, if the electrodes are supported by a blanketsubstrate, the plasma generated below the blanket substrate should bemore directed at the contaminated surface and more efficientlydecontaminate the surface. Another alternative would incorporate stripsof the flexible cloth or fiber thread material into the spaces betweenadjacent dielectric material covered electrodes 12 a and betweenadjacent bare electrodes 18 b. While such a filler material is not berequired, it would likely add both structural and plasma stability tothe blanket.

The spatial extent of the non-thermal plasma discharge generated atintersections 15 b of bare electrodes 18 b and dielectric material 14 acovered electrodes 12 a will determine the spacing between adjacentparallel electrodes of like kind. Preferably, these electrodes will bespaced apart such that there is a small amount of overlap in the coronadischarges produced at each intersection, and the spacing will also be afunction of the voltage differential applied between electrodes 12 a andbare electrodes 18 a. Too much overlap in the corona discharge wouldresult in a plasma blanket that incorporates more bare electrodes 18 band dielectric material 14 a covered electrodes 12 a than is necessary,thus driving up the cost of the plasma blanket. A plasma blanket whichhas too little or no overlap of corona discharges will have too fewelectrodes and will not effectively treat the entire surface or objectthat is contaminated with the biological or chemical agents. The appliedpower will depend upon the total area of the plasma blanket. It isexpected that only about 1 watt/cm² should be sufficient to treat asurface with the plasma blanket.

While no separation is required between intersections 15 b of the bareand dielectric covered electrodes, it is envisioned that nonconductiveconnectors (not shown) can be used to maintain a desired uniform spacingbetween bare electrodes 18 b and dielectric material covered electrodes12 a. Such connectors can include plastic clips or ties as those ofordinary skill in the art will readily understand.

FIG. 4 illustrates yet another embodiment of a plasma blanket 17 a thatcomprises a single bare electrode 18 c that is formed in an accordionfold or pleated configuration, and at least one dielectric materialcovered electrode 12 a. Bare electrode 8 c is formed of a metallic foil,a thin metal sheet, a mesh, or other conductive sheet through whichelectrode 12 a covered with dielectric material 14 a passes. As withother embodiments, the corona discharge is generated at each ofintersections 15 c between dielectric material covered electrode 12 aand bare electrode 18 c. While FIG. 4 illustrates only a singledielectric material 14 a covered electrode 12 a, it is envisioned that aplurality of such dielectric covered electrodes extending generallyparallel to each other will be used. As discussed above, the distancebetween the pleats of bare electrode 18 c and dielectric material 14 acovered electrodes 12 a preferably creates overlapping corona dischargesat each intersection of the bare electrode with the dielectric coveredelectrodes. Bare electrode 18 c can be in point contact with dielectriccovered electrode 12 a, or there can be a gap between them.

Plasma blanket 17 a would have less dimensional flexibility than thewoven plasma blanket 17 shown in FIG. 3. However, accordion plasmablanket 17 a could be very useful in decontaminating flat surfaces. Oneadvantage of the accordion configuration is that it is a relativelysimple design that would be easier to manufacture than woven plasmablanket 17. While not shown, it is envisioned that a non-conductingmaterial may be added to one side of plasma blanket 17 a, such that thenon-conducting material forms a plane that supports the peaks of thepleats of bare electrode 18 c, holding them away from the contaminatedsurface. This variation would be useful if bare electrode 18 c werefabricated from a wire mesh. In this case, reactive species generated bythe plasma discharge that are migrating away from the contaminatedsurface would be reflected from the non-conducting material back towardthe contaminated surface, and would pass through bare electrode 18 c toreach the contaminated surface. If bare electrode 18 c is solid or anon-conducting material is not provided, the reactive species generatedby the plasma discharge that are directed away from the contaminatedsurface would likely not reach the contaminated surface.

FIG. 5 illustrates a preferred embodiment of a plasma blanket 17 b. Aplurality of distributed plasma reactors 16 a are arranged generallyparallel to each other and are attached to a flexible substrate 34, suchthat the distributed plasma reactors cover most of the surface offlexible substrate. Each distributed plasma reactor 16 a is identical tothe embodiment illustrated in greater detail in FIG. 2. The distributedplasma reactors 16 a are spaced apart on flexible substrate 34 such thatthere is an overlap in the area in which the corona discharges areproduced by adjacent distributed plasma reactors. A typical spacing, forexample, might be about 0.25 inches; however, the same considerationsapply in determining the spacing of the corona discharge generators, asdiscussed above in regard to the other embodiments. Plasma blanket 17 bis energized by a high voltage source 26 a, which supplies a voltage ofseveral thousand volts, e.g., 4,000 volts peak-to-peak, applied betweenthe bare electrodes and the dielectric material covered electrodes.Flexible substrate 34 must be non-conductive. The flexible substrate maybe a woven material, such as a fiberglass mat, or a non-woven sheet of amaterial such as a plastic.

The above embodiments have all been distributed plasma reactors usingsilent corona discharge to generate non-thermal plasma discharges at theintersections of dielectric covered electrodes and bare electrodes.FIGS. 6A, 6B, and 7 illustrate embodiments in which a non-thermal plasmadischarge is produced through a slightly different process. FIG. 6Ashows a pulse type corona discharge generator 16 c that includes anelectrode 12 b covered with a dielectric material 14 a. Electrode 12 bpreferably comprises a multi-strand wire. An end of electrode 12 b isunraveled into its individual strands 32. When electrode 12 b isenergized with a Tesla coil generator 38, a corona discharge 30 demanates from the ends of each individual strand, as shown by areference numeral 15 e. The electric fields are concentrated at the endsof the strands, from which the plasma emanates.

It should also be noted that the pulsed discharge used to energize thepreceding embodiment, as discussed above, is distinguishable from priorart uses of a plasma spray to deposit a solid material onto a substrate.The non-thermal plasma generated by pulse type corona dischargegenerator 16 c is not employed for ionizing a solid material that isthen deposited on a substrate, but instead is used to ionize ambientair, which produces reactive species that decontaminate a target bydestroying biological and/or chemical agents.

FIG. 6B illustrates how corona plasma discharge generator 16 c is usedto decontaminate a surface 36, which is coupled to a ground 42. Bygrounding the object to be treated, the zone of the corona discharge isenlarged and corona discharge generator 16 c can be disposed at greaterdistances from surface 36, while remaining effective in destroyingchemical and biological contaminants on the surface. It is contemplatedthat corona discharge generator 16 c may be handheld and its coronadischarge manually applied and moved over the surface(s) of an object tocompletely decontaminate those surfaces. Generally, if the object issitting on the ground, it will be sufficiently grounded to provide theexpanded zone of corona discharge shown in FIG. 6B, so that a separateconnection to ground through a wire or other conductor will not berequired.

While FIGS. 6A and 6B show a dielectric 14 a, it is important tounderstand that in these embodiments, the non-thermal plasma isgenerated by a pulse discharge device, not a barrier discharge device.Thus, dielectric 14 a can be removed without effecting the ability ofthese embodiments to generate a non-thermal plasma.

FIG. 7 illustrates a plasma blanket comprising distributed plasmareactors of the pulsed discharge type. A plasma blanket 17 f includes aflexible substrate 34, which supports a plurality of dielectric spacers14 b and pin or point electrodes 12 c. Plasma blanket 17 f is energizedby Tesla coil generator 38, which is connected to a voltage/power source26 a (which may be a line voltage source, a portable generator, orbattery/inverter supply, none of which is shown in the Figure).Preferably, surface 36 is connected to a ground 42 to ensure that zone15 f of the plasma discharge is expanded, in a manner similar to thatshown in FIG. 6B. The corona discharge around point electrodes 12 edecontaminates surface 36. Dielectric spacers 14 b maintain the pointelectrodes at a fixed spacing apart from surface 36, preventing thepoint electrodes from shorting to ground by contact with surface 36. Itwill be apparent that plasma blanket 17 f can be moved laterally oversurface 36 to cover an expanded area of the surface. In addition, it iscontemplated that substrate 34 may be made of a flexible material thatwill enable the plasma blanket to conform to non-planar surfaces, solong as dielectric spacers 14 b maintain the desired spacing between thepoint electrodes and the grounded surface being decontaminated.

The preceding embodiments have been directed to distributed plasmareactors that have been configured as a plasma blanket to decontaminatesurfaces or objects. However, it should be noted that any of thepreceding embodiments can also be used to decontaminate a fluid whichpasses through the non-thermal plasma generated by these distributedplasma reactors. FIGS. 9–12 illustrate embodiments of distributed plasmareactors that are particularly well suited to decontaminate fluidstreams. FIGS. 8A and 8B illustrate preferred embodiments of the type ofsilent corona discharge generators used in the distributed plasmareactors of FIGS. 9–12, in which the bare electrode is a sheet orconducting mesh.

In FIG. 8A, dielectric material 14 a covered electrode 12 a is disposedgenerally perpendicular to a bare electrode 18 d, which is formed as asheet. The corona discharge phenomenon arises at an intersection 15 d ofdielectric material 14 a coated electrode 12 a and bare electrode 18 d.The intersection may comprise a gap, or bare electrode 18 d can actuallybe in point contact with dielectric material 14 a. Bare electrode 18 dmay be formed of a metal foil, a metal mesh, or other conductivesheet-like material. A distributed plasma reactor can be fabricated suchthat bare electrode 18 d is the size of the finished reactor.Alternately, a plurality of smaller bare electrodes 18 d can be mountedin spaced-apart array on a substrate (not shown).

It should be noted that several possibilities arise depending on thecharacteristics of intersections 15 d between bare electrode 18 d anddielectric material covered electrode 12 a. If intersections 15 d arerigid and do not allow for movement about the intersection, theresulting distributed plasma reactor will not exhibit much dimensionalflexibility. For most fluid stream applications, this issue will notpresent a problem. It is possible that in some situations, it would bedesirable to provide a decontamination system adapted to simultaneouslyor individually treat a surface and/or a fluid. In such an application,dimensional flexibility would be desirable, and it is preferable thatintersections 15 d between the electrodes be sufficiently flexible toallow dielectric material 14 a and electrode 12 a to be moved from aposition essentially perpendicular to bare electrode 18 d as shown inFIG. 8A, to a more acute angle, generally as illustrated in FIG. 8B.

FIG. 9 illustrates a distributed plasma reactor 17 c comprising a singlesheet electrode 18 d and a plurality of electrodes 12 a covered withdielectric material 14 a. Preferably the spacing between the pluralityof dielectric material covered electrodes is such that the plasmadischarges that are created at the intersections between theseelectrodes and sheet electrode 18 d will overlap. Any fluid flowing pastthese intersections will be exposed to the plasma discharged andbiological and/or chemical contaminants conveyed by the fluid will bedestroyed thereby.

While distributed plasma reactor 17 c is expected to be mostbeneficially employed to treat fluids, bare electrode 18 d is in a sheetconfiguration and thus distributed plasma reactor 17 c could be used totreat surfaces in the same manner as the previously discussed plasmablanket embodiments. If distributed plasma reactor 17 c is employed totreat a surface, the length of electrodes 12 a can be adjusted tocontrol the distance between the contaminated surface and theintersections where the corona discharges are produced. The coronadischarge phenomenon arises at intersections 15 d and will have a finiteextent. The effective range of the plasma discharge, which is primarilydue to the reactive species generated by the ionization of the ambientgas molecules in the plasma region, will determine how much separationbetween the contaminated surface and intersections 15 d is permissible.These reactive species will migrate very quickly out of the plasma zoneand onto the contaminated surface. The reactive species migrating awayfrom the contaminated surface can be redirected toward that surface. Bycontrolling the length of electrode 12 a, and thus the separationbetween the contaminated surface and bare electrode 18 d, the generatedplasma may be selectively directed onto or kept from direct contact withthe contaminated surface.

It is contemplated that electrode 12 a may have a different length aboveone surface of bare electrode 18 d than below the opposite surface ofbare electrode 18 d. Distributed plasma reactors 16 b can then beoriented so that the longer length of electrodes 12 a are directedtoward the contaminated surface to prevent the plasma from directcontacting the contaminated surface, or can be oriented with the shorterlength of electrodes 12 a toward the contaminated surface to direct theplasma onto the contaminated surface, merely by turning the plasmablanket over. Alternately, dielectric material 14 a covered electrode 12a can be slidably attached to bare electrode 18 d, such that the lengthof dielectric material 14 a covered electrode 12 a between thecontaminated surface and bare electrode 18 can be selectively varied bythe user.

FIG. 10 illustrates a distributed plasma reactor 17 d that includes botha plurality of electrodes 12 a covered with dielectric material 14 a aswell as a plurality of bare sheet electrodes 18 d. This embodimentallows a distributed plasma reactor to be fabricated that has plasmagenerating zones not just at the surfaces of the reactor where eachdielectric material covered electrode intersects bare sheet electrode 18d, but also within interior regions between the plurality of sheetelectrodes, where the decontaminating effects of the plasma are providedas well. Such a distributed plasma reactor can be used to treatcontaminated fluids flowing through the interior regions, as is shown bya fluid flow 50. It should be noted that fluid flowing through thepassages in electrode 18 d (when the electrode is constructed of amesh), as shown by a fluid flow 50 a, will be similarly exposed to thenon-thermal plasma and thus, be similarly decontaminated.

Distributed plasma reactor 17 d would be particularly applicable for usein decontaminating air flowing through a HVAC system, to destroybiological agents (such as disease causing microorganisms, spores,fungi, or allergens) and chemical agents that are conveyed by the air.As above, preferably the spacing between the plurality of dielectricmaterial 14 a covered electrodes 12 a is such that overlapping plasmadischarges will be created at intersections 15 d between sheetelectrodes 18 d and dielectric material covered electrodes 12 a.Furthermore, the spacing between the bare sheet electrodes also shouldbe such that overlapping plasma discharges will be created within theinterior region as well.

FIGS. 11 and 12 illustrate a distributed plasma reactor 17 e thatincludes an internal treatment volume 48 defined between twospaced-apart bare sheet electrodes 18 e and 18 f, which are generallyparallel to each other. Distributed plasma reactor 17 e also has aplurality of electrodes 12 a covered with dielectric material 14 a thatpass through upper bare sheet electrode 18 e and lower bare sheetelectrode 18 f. Preferably, distributed plasma reactor 17 e includessufficient dielectric material covered electrodes 12 a that are spacedso as to provide an overlap of the resulting corona discharge plasmazones, which will be particularly effective in decontaminating a fluidflowing through internal treatment volume 48 that is contaminated withbiological agents (such as disease causing microorganisms, spores,fungi, or allergens) and/or chemical agents. Sheet electrodes 18 e and18 f should be sufficiently close together such that the entire internaltreatment volume 48 is saturated with non-thermal plasma. Distributedplasma reactor 17 e is thus particularly applicable to decontaminatingair or gas streams in an HVAC system or if made smaller, for use in anair purifying respirator or gas mask, to decontaminate air breathed bypersonnel that may convey biological or chemical warfare agents. Thisembodiment is also useful for decontaminating a liquid having minimalconductivity. It should be noted that while the dielectric 14 a coveredelectrodes 12 a comprise a barrier discharge corona generator (as shownschematically in FIG. 1), the embodiment detailed in FIGS. 11 and 12would operate if a pulsed corona discharge generator (as shown in FIG.6A) was used instead.

FIG. 12 illustrates how the plasma discharges of distributed plasmareactor 17 e can be used to decontaminate a fluid. When distributedplasma reactor 17 e is energized by applying several thousand volts(A/C) of potential between electrodes 12 a and bare sheet electrodes 18e/18 f, a plasma discharge is produced in a zone 30 a above bare sheetelectrode 18 e, at a zone 30 b within internal treatment volume 48, andin a zone 30 c underneath bare sheet electrode 18 f at each intersection15 d. Plasma discharge in zone 30 b is perhaps most useful indecontaminating fluid flowing through internal treatment volume 48, asshown by fluid flow 50. The fluid can also be caused to flow throughopenings in the upper surface of bare sheet electrode 18 e and baresheet electrode 18 f (when such electrodes are in a mesh configuration),through zones 30 a and 30 c, as is shown by fluid flows 50 a. While notshown in FIG. 11 or 12, it should be noted that multiple internaltreatment volumes 48 can be created with the addition of further sheetelectrodes disposed adjacent and generally parallel to either sheetelectrode 18 e or 18 f.

Internal treatment volume 48 may be filled with a packing material toimprove the reactor performance. The resulting improvement inperformance is due to increasing the residence time of the contaminantswithin the plasma zone of internal treatment volume 48. Additionally, acatalytic packing material can be selected to further enhance thereactor performance.

The concept and benefits of altering residence time are well establishedin the art of fluid and gas chromatography. It is known that when acontaminant in a carrier fluid is introduced into a packed column ofgranular material, the contaminant interacts with the packing to slowits procession through the packed column relative to the carrier fluid.The primary reason for the difference in residence times is that acarrier fluid is selected so that the size of the contaminant moleculesare substantially larger than the size of the carrier fluid molecules.If the contaminant is known, then the packing material may be selectedsuch that the packing material has greater affinity for the contaminantthan the carrier fluid, so that the passage of the contaminant throughthe packed column is further impeded. When internal volume 48 of plasmareactor 17 e is filled with a packing material, this chromatographicaffect permits higher fluid flow rates to be attained, while maintaininga very high processing efficiency for the contaminant, which resides inthe plasma for a longer period time.

The form of the packing material can be granular, tubular, ring,spheroidal or spherical, fibrous, foam or aggregate. Preferably thepacking material has a resistivity greater than a like volume of thefluid being processed and a dielectric constant equal to or greater thanthat of the fluid (for air, the dielectric constant equals one). Thepacking surface may be inert or catalytic in nature. Surfacesimpregnated with active metal catalysts have been demonstrated to bemore effective than inert or unimpregnated packing materials. Pyrexbeads, pyrex rings, platinum-palladium-rhodium catalyst spheroids,alumina spheroids, and other materials have been successfully utilizedas packing materials in thermal and plasma reactor columns and should beequally effective in the present invention. The packing material can beporous or nonporous; however, greater adsorptive capability is preferredfor packings used in high performance plasma discharge reactors. Apacking material can improve reactor performance due to catalyticeffects alone, rather than due to any adsorptive capability. Preferably,a packing material the exhibits both adsorptive and catalytic propertieswill be selected.

A particular advantage exhibited by the combination of a packedtreatment area and a distributed plasma reactor is the surface cleaningof the packing by the non-thermal plasma. A common problem in thermalcatalytic reactors is that the packing eventually becomes blocked orpoisoned by contaminant condensates or reaction products, such asinorganic salts or oxides. The reactive species generated by thenon-thermal plasma that destroy the contaminants also interact with thesurfaces of the packing material to purge any such condensates orreaction products. The continual cleaning of the surfaces by thesereactive species prevents saturation or poisoning of the packingmaterial. This cleaning process insures optimum performance ofdistributed plasma reactor 17 e.

FIG. 13 illustrates an embodiment of a distributed plasma reactor 17 gof the pulsed discharge type in which an internal treatment volume isfilled with a packing material that comprises a plurality of small“secondary” coil covered dielectrics. A “primary” helical coil 64surrounds an internal treatment volume 58. Primary coil 64 is connectedto and energized by tesla coil 38 at a first end, and connected toground 42 at a second end. Prior to filling internal treatment volumewith the packing material, a contaminated object 62 is placed insideinternal treatment volume 58. Preferably, contaminated object 62 israised above the floor of internal treatment volume 58 by supports 60,to ensure that the lower surfaces of contaminated object 62 are bathedin plasma. Once contaminated object 62 is in position, all of theremaining void or space within internal treatment volume 58 is filledwith a plurality of small secondary coils 66. When primary helical coil64 is energized by tesla coil 38, inductive coupling between the primaryhelical coil and the plurality of small secondary coils 66 causesinternal treatment volume 66 to be bathed in a non-thermal plasma. Thisplasma effectively treats contaminated object 62 in the manner describedabove.

The terms primary coil and secondary coil have been used to describe thecoils in this particular embodiment because of the similarity that thisapparatus shares with a tesla coil, namely the inductive couplingbetween a primary coil and a secondary coil via an air gap. One benefitof this embodiment is that the inductive coupling helps create a large,stable plasma region. This particular embodiment does require highexcitation voltages and high power levels, and as such, is expected tobe better suited to non-portable applications. However, this embodimentdoes share the feature with other embodiments that the non-thermalplasma is generated at a plurality of locations distributed throughout atreatment volume.

Once the treatment of an object is completed, the secondary coils areremoved from the treatment volume so that the decontaminated object maybe removed. The secondary coils are saved for re-use. It is alsocontemplated that instead of placing an object inside of the internaltreatment volume, a fluid could be passed through the internal treatmentvolume and similarly decontaminated.

FIG. 14 is an isometric schematic view of a one of the plurality ofsmall secondary coils used to fill the remaining void or space ofinternal treatment volume 58 in distributed plasma reactor 17 g.Secondary coil 66 a includes many coils 15 g of a conductor extendingaround a dielectric core 70, which is preferably in the form of eitheran ellipse, a rod, or a bead. Coils 15 g can be of a fine wire or ametallic trace deposited on the surface of dielectric core 70 and mayoptionally be covered with a dielectric layer (not shown).

FIG. 15 is a isometric schematic view of one embodiment of a primarycoil 64 a to be used in conjunction with distributed plasma reactor 17g. This embodiment comprises a coil with a plurality of spark gaps 68.The high voltage this embodiment requires can be generated by addingmore turns to primary coil 64. One drawback related to this embodimentis an inherent reduction in the rate at which the primary coil can beswitched. As an alternative, primary coil 64 a can be used. Primary coil64 a includes a plurality of spark gaps around the perimeter ofdistributed plasma reactor 17 g.

FIG. 16 is a block diagram illustrating the functional components of adistributed plasma reactor decontamination system in accord with thepresent invention. A battery 20 (or other power source) is connected toa control logic and electric interface 22. A user interface 24 isconnected to the control logic and electric interface, enabling a userto adjust the voltage level of the system, set the pulse duration, andcontrol other parameters such the duration of the decontaminationprocess. Logic control interface 22 is connected to a high voltageinverter 26, which converts the battery voltage, e.g., 12 volts directcurrent, to a high voltage signal, e.g., 4,000 volts peak-to-peak. Theoutput voltage from high voltage inverter 26 is attached to adistributed plasma reactor 28, so that the potential difference isapplied between the bare electrodes and the dielectric material coveredelectrodes. While a battery allows the distributed plasma reactor to bemore readily portable, the distributed plasma reactor can be adapted tobe energized by other power sources, such as a line voltage sourceavailable at the location of the contamination, or a portable generator.

In an experiment conducted with a distributed plasma reactor like theembodiment shown in FIG. 5, a plasma blanket measuring about 3 in. perside was fabricated. A 5 watt power source was used to energize thecorona discharge plasma generators in the plasma blanket with a voltageof about 4,000 volts peak-to-peak. It was found that a slidecontaminated with Bacillus globigii was substantially decontaminated byexposure to the plasma discharge of the plasma blanket for a timeinterval of only about 5 minutes.

It will be apparent that a personal decontamination system can beprovided with the present invention by making each of the elements shownin FIG. 13 sufficiently small and compact to be carried by anindividual. This decontamination system can then be incorporated into agas mask to decontaminate ambient air conveying biological or chemicalagents. Larger portable decontamination systems can use a plasma blanketembodiment of a distributed plasma generator to decontaminate surfacesor objects that have been contaminated with biological or chemicalagents. By using a flexible plasma blanket that is draped over orwrapped about an object, irregularly-shaped objects, including militaryvehicles such as tanks, can be decontaminated. Distributed plasmagenerators can also be incorporated into HVAC systems through which airis supplied to vehicles or buildings to decontaminate the air bydestroying biological or chemical agents carried by the air. Particlessuch as seeds or herbs can be decontaminated by exposure to the plasmadischarge produced by the present invention to destroy harmful agentssuch as insecticides, herbicides, molds and fungi that are on thesurface of the seeds or herbs. The present invention can also be usedfor decontaminating soil particles that have become contaminated byexposure to chemicals (or other contaminants) released into the soil, orfor preparing soils for planting by destroying molds naturally occurringin the soil. Plasma decontamination of fluids, such as air, can becarried out with any of the embodiments of the present invention inwhich a fluid stream can be conveyed through a region of plasmadischarge, particularly the embodiments shown in FIGS. 9–12, to destroybiological or chemical contaminants in the fluid.

One of the byproducts of a plasma discharge is ozone. Accordingly, thepresent invention is also useful for generating ozone, which is usableto oxidize contaminants in drinkable liquids or on foodstuffs.

Although the present invention has been described in connection with thepreferred form of practicing it, those of ordinary skill in the art willunderstand that many modifications can be made thereto within the scopeof the claims that follow. Accordingly, it is not intended that thescope of the invention in any way be limited by the above description,but instead be determined entirely by reference to the claims thatfollow.

1. A method for decontaminating a surface on which either a biologicalor chemical toxic agent has been deposited, comprising the steps of: (a)providing a power source that produces a voltage sufficiently great togenerate a non-thermal plasma discharge and a plasma blanket that issufficiently flexible to be able to be draped and wrapped around anobject, the plasma blanket comprising a generally, sheet non-thermalplasma generator configured to distribute a non-thermal plasma dischargeto the surface adjacent to the plasma blanket when activated by thepower source; (b) positioning the plasma blanket adjacent to the surfacethat is to be decontaminated; and (c) activating the non-thermal plasmagenerator with the power source, producing the non-thermal plasmadischarge that destroys the toxic agent, thereby decontaminating thesurface.
 2. The method of claim 1, wherein the surface is non-planar andis part of an irregularly-shaped object, further comprising the step ofdraping the plasma blanket over the irregularly-shaped object, so theplasma blanket is proximate to the non-planar surface.
 3. The method ofclaim 1, wherein the non-thermal plasma generator is activated for atime interval of less than ten minutes to decontaminate the surface. 4.The method of claim 1, wherein the non-thermal plasma generator is adistributed plasma reactor, comprising a plurality of electrodesconfigured to generate a non-thermal plasma at a plurality of differentlocations distributed across the plasma blanket, each of the pluralityof electrodes being adapted to be disposed adjacent to the surface thatis to be decontaminated, such that non-thermal plasma generated by theplurality of electrodes is distributed across a plurality of locationson the surface to be decontaminated.
 5. The method of claim 1, whereinthe non-thermal plasma discharge is generated using a high voltagepulse.
 6. The method of claim 1, further comprising the step of movingthe non-thermal plasma generator over the surface, to decontaminate alarger area of the surface.